Many forms of industrial equipment and other vehicles use disc braking systems which, during braking, generate a significant amount of heat which needs to be controlled. Further, such systems often require a steady supply of lubrication to ensure efficient operation and long life. One method for dispersing the generated heat and providing lubrication is to supply a flow of cooling and lubricating fluid directly to the brake components within the brake housing. The fluid used in such brakes provides both the cooling and lubricating functions and is often an oil based product. Such brakes are often referred to as “wet” brakes because of the constant supply of fluid to the interior chamber of the brake.
Wet brakes that include a disc assembly that has alternating rotating and stationary discs are referred to as multi-disc brakes. During “roading conditions” the brake pistons are positioned to allow free spinning of the rotating discs and a shaft within a cavity of the brake. A “braking event” occurs when brake pistons or springs of the brake cause the rotating discs to engage the stationary discs, generating friction forces that act to prevent rotation of the shaft. A cooling effect is most needed during the braking event due to the high amount of heat generated by the friction energy between the rotating discs and stationary discs.
While continually providing of fluids to the brake chamber is effective in cooling and lubricating the brake, other problems exist in such a design. Specifically, the inner cavity of the brake is full of fluid during roading conditions as well as during a brake event, when the fluid is most needed for cooling. This causes the rotating discs to experience significant drag as they rotate through the fluid, causing significant oil shear, generating heat, and causing loss of power. Horsepower losses affect the output and drive-train efficiency of the vehicle.
In view of these problems, it is evident that the need exists for a brake which provides sufficient cooling and lubrication during braking conditions but which reduces the drag upon the disc assembly during roading conditions.